Energy Meter Sampling Rate Conversion for Line Frequency Jitter
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Solution Overview
Problem
Existing energy metering technologies face complications in accurately measuring energy consumption due to non-integer multiple sampling rates and line frequency jitter in alternating current power distribution systems, which complicates energy measurement calculations.
Innovation Solution
A method and system for sampling rate conversion of power signals that involves detecting the fundamental frequency of an analog poly-phase signal, determining a second sampling rate based on this frequency, resampling the signal, and using Fast Fourier Transformation to calculate phase angles and adjust the signal, thereby facilitating accurate and efficient energy measurements independent of the ADC sampling rate and immune to line frequency jitter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the ADC sampling rate is set to be an integer multiple of the line frequency, then the energy measurement calculation is simplified, but the system becomes sensitive to line frequency deviation and jitter
Solution Approach 1:
The patent implements a dynamic resampling mechanism where the sampling rate is continuously adjusted to track the fundamental frequency of the power signal. The system detects frequency deviations in real-time and modifies the sampling rate accordingly, transforming the static sampling approach into a dynamic one that adapts to frequency variations, thereby maintaining measurement accuracy without requiring the sampling rate to be a fixed integer multiple of the line frequency.
Solution Approach 2:
The system changes the sampling rate parameter dynamically based on the detected fundamental frequency. By continuously monitoring the power signal frequency and adjusting the sampling rate to match (rather than requiring it to be an integer multiple), the system resolves the contradiction between calculation simplicity and reliability under frequency deviation.
2Measurement precision
If the sampling rate is fixed at a high value to ensure adequate sampling, then measurement accuracy is improved, but energy consumption and processing load increase
Solution Approach 1:
The patent employs dynamic resampling where the sampling rate is adjusted in real-time based on the detected fundamental frequency and measurement requirements. Instead of using a fixed high sampling rate, the system dynamically determines the appropriate sampling rate, reducing unnecessary sampling operations and thereby lowering energy consumption while maintaining adequate measurement precision.
Solution Approach 2:
The sampling rate parameter is changed dynamically rather than being fixed. The system adjusts the sampling rate according to the actual power signal characteristics and measurement needs, optimizing the balance between measurement precision and energy consumption by using the minimum necessary sampling rate at any given time.
3Reliability
If the sampling rate is adjusted to track line frequency variations, then measurement accuracy under frequency deviation is improved, but the complexity of the sampling rate conversion system increases
Solution Approach 1:
The patent implements preliminary frequency detection and analysis before performing the actual energy measurement. By detecting the fundamental frequency in advance and pre-calculating the appropriate sampling rate, the system prepares the optimal sampling parameters beforehand, which simplifies the overall measurement process and reduces the complexity of real-time sampling rate conversion during actual measurements.
Solution Approach 2:
The system introduces an intermediate frequency detection and analysis stage that acts as a mediator between the power signal and the sampling process. This intermediary component analyzes the power signal characteristics and generates appropriate sampling rate control signals, thereby simplifying the complexity of direct sampling rate adjustment by breaking it into manageable stages.
4Measurement precision
If phase angle compensation is performed for each cycle of the resampled signal, then measurement accuracy is improved, but processing time and computational load increase
Solution Approach 1:
The patent performs phase angle detection and compensation calculations in advance during the frequency analysis stage. By pre-calculating the phase angle offsets based on the detected fundamental frequency and signal characteristics, the system prepares compensation values before the actual energy measurement, reducing the processing time required during each measurement cycle while maintaining high measurement precision.
Data Source
AI summary
A method of processing power signals is provided. The method includes: receiving an analog poly-phase signal associated with power delivered using alternating current (AC); converting the analog poly-phase signal to a digital poly-phase signal sampled at a first sampling rate; detecting a fundamental frequency of the analog poly-phase signal; determining a second sampling rate, wherein the second sampling rate is based on and tracks the fundamental frequency; resampling the digital poly-phase signal at the second sampling rate; for each cycle of the resampled digital poly-phase signal: transforming the resampled digital poly-phase digital signal to a frequency-domain signal; calculating a phase angle of the reference voltage component; adjusting the resampled digital poly-phase signal by compensating the calculated phase angle; and transforming the adjusted resampled digital poly-phase signal to an updated frequency-domain signal using FFT; and calculating one or more measurements based on the updated frequency-domain signal.